Harmonic producer



March 14, 1939.. J. M. MANLEY 2,150,386

HARMONIC PRODUCER Filed Sept. 30, 1957 2 Sheets-Sheet l /6 000 m0 EVENl0 "mum/n;

FILTERS i, FIG? D I 4 V n n n A J zil FIQ 3 7i 7%; 3 377- 5 l n n V77 Vn A t,

IN VE N TOR JM. MANLEV JW I ATTORNEY March 14,1939. J MANLEY 2,150,386

HARMONIC PRODUCER Filed Sept. 30, 1937 2 Sheets-Shem- 42 /.0 Q00 X EVENy 000 EVEN q 2. FIGS- 3 g E E n t I p 0 I z z'r jl a F/G.4 B

INVENTOR JM. MANLE) ATTORNEY Patented Mar. 14, 1939 UNITED STATESHARMONIC PRODUCER Jack M. Manley, East Orange, N. J., assignor to BellTelephone Laboratories, Incorporated, New York, N. Y., a corporation ofNew York Application September 30, 1937, SerialNo. 166,519

'7 Claims. This invention relates to harmonic generators I and moreparticularly to harmonic generatorsof the magnetic type utilizing adirect current bias to produce both odd and even harmonics and toaccentuate a preselected harmonic.

In the copending application of L. R. Wrathall. Serial No. 77,989, filedMay 5, 1936, and assigned to applicants assignee; a system utilizing asaturable-core coil is described for producing a series of relativelysharp pulses having a uniform time spacing therebetween and whereby arange of odd harmonics is produced. The present invention cotemplatesthe provisions of applying a direct current bias to the saturable-corecoil to shift each of the pulses by a predetermined amount depending onthe magnitude of the bias. This shift of the pulses provides a wave formsuch that both odd and even harmonics are produced in the outputcircuit. Also, the bias may be so proportioned that the amplitude of aneven harmonic is produced with a maximum value while the amplitudes ofthe odd harmonics lying adjacent thereto are suppressed or that theamplitude of an odd harmonic is produced with a maximum value while theamplitude of the even harmonics lying adjacent thereto are suppressed. Aharmonic having a maximum amplitude relative to the suppressedamplitudes of adjacent harmonics is useful in certain systems forsynchronizing purposes, particularly in systems where the synchronizingharmonic is changed from time to time over a range of odd and evenharmonics.

It is an object of this invention to simultaneously produce odd and evenharmonics.

It is another object of this invention to accentuate the amplitude of apreselected harmonic while at the same time suppressing the amplitudesof the harmonics lying adjacent thereto.

It is a further object of this invention to produce a certain range ofboth odd and even harmonies having uniformly large amplitudes.

The invention will be more readily understood from the followingdescription taken together with the accompanying drawings in which:

Fig. 1 is a diagrammatic circuit illustrating the preferred form of theinvention;

Fig. 2 shows a wave form resulting from the operation of Fig. 1 withoutbias; and

Figs. 3, 4 and 5 illustrate the operation of Fig. 1 with bias inaccordance with the invention.

Referring to Fig. 1, an alternating current source l0 applies afundamental wave through a tuned circuit II to the primary of asaturablecore coil l2. A secondary or output circuit l3 for the coilcomprises a condenser l4, coupling transformer l5 and a group [6 of oddand even harmonic-selective filters. As described in the aforementionedcopending application of L. R. Wrathall the constants of the outputcircuit are so proportioned as to produce a series of alternatingpulses, each of brief duration and representing the discharge ofcondenser i4 through. a substantially resistive output circuit. Thesepulses illustrated in Fig. 2 have a uniform time spacing therebetweenand occur periodically with the period of the fundamental wave toproduce in the output circuit a group of odd harmonics having uniformlylarge amplitudes. Curve A in Fig. 4 shows the magnetizationcharacteristic of the saturable-core of the coil 12 as the fundamentalcurrent I: is impressed thereon to eiiect the wave form illustrated inFig. 2. In curve A of Fig. 4, it is seen that the inductance of the coilI2 is a maximum for the positive half-cycle between the points C and D,and again a maximum for the negative half-cycle between the points E andF.

In the present invention a source ll of direct current is applied to thesaturable-core coil through a choke coil [8 and an adjustable resistancel9. This direct current bias serves to shift the magnetizationcharacteristic of the saturable-core coil shown by curve A of Fig. 4 tothat illustrated by curve B of Fig. 4 by an amount b that depends on themagnitude of the direct current voltage.

The wave shape shown in Fig. 3 and resulting from the magnetizationcharacteristic curve B produces in the output circuit both odd and evenharmonics whose range is substantially the same as that produced by thewave shown in Fig. 2. The amount of the pulse shift in pt can be readilydetermined from the following equation:

tude of the magnetization force of the wave Ir. The equation isapproximately correct if b 1 r e It is to be understood that therelative heights of the peaks of the pulses illustrated in both Figs.

2 a,1so,aas

2 and 8 are substantially identical. This is true since the shape of thepulse is determined by the constants of the saturable-core coil andoutput circuits in Fig. 1 and these are unchanged for the waves shown inFigs. 2. 3 and 4.

Referring to curve B of Fig. 4, the inductance of the saturable-corecoil is a maximum for the positive half-cycle of the fundamental currentI: between the points G and H and again a maximum for the negativehalf-cycle between the points K and L. Thus in curve B the saturablecorecoil attains minimum inductance in a positive direction sooner than'incurve A and in a negative direction later than in curve A. In

other words, according to curve B the condenser in curve A.Consequently, the positive pulse P of Fig. 3 occurs sooner than thecorresponding pulse P of Fig. 2'and the negative pulse N of Fig. 3occurs later than the corresponding pulse N of Fig. 2.

The direct current bias I) may be proportioned to suppress or accentuatea particular odd or even harmonic of the fundamental alternating cur-.rent wave I: as desired. That is, a particular odd harmonic is producedwith maximum amplitude while the even harmonics lying adjacent theretoare suppressed or a particular even harmonic is produced with maximumamplitude while the odd harmonics lying adjacent thereto are suppressed.The amount of direct current bias b required to produce a preselectedharmonic with maximum amplitude can be readily calculated from thefollowing equations:

b r b {hp-5 tr" where r s b is the magnetizing force due to the biasingvoltage, P is the amplitude of the magnetizing force of the wave 11 andn in Equation a is a particular even harmonic while 11 in Equation 1) isa particular odd harmonic. If

h l P 6 the above equations are approximately correct.

In Fig. 5 it is seen that when an even harmonic, say, for example,harmonic X has a maximum amplitude, the two odd harmonics lying adjacentthereto are suppressed and that when an odd harmonic, say, for example,harmonic Y has a maximum amplitude, the even harmonics lying adjacentthereto are suppressed. It is understood that the distribution ofharmonics shown in Fig. 5 is an amplitude factor to be applied to thedistribution of harmonics obtained by the wave shape of Fig. 2, which isproduced in accordance with the copending application of L. R. Wrathall,supra. Thus the factor, whose maximum value is 1.0, must be multipliedby the harmonic amplitudes obtained in Wrathall's harmrmic distributionin order to ascertain the actual value of the amplitudes.

InFlg.5itisalsoseenthat for alimitedrange in the vicinity of theintersections of the odd and even factors, the amplitudes of both oddand even harmonics will be relatively large and substantially uniform,depending in an inverse manner on the width of the range of harmonics.

Having ascertained the amplitude of an accentuated harmonic in themanner indicated above,

the extent of the suppression of the adjacent harmonics can bedetermined as follows:

If the amplitude of an even harmonic n. is produced with maximum value,then the ratio of the amplitude of the odd harmonics mil to the evenharmonic n. is

If, for example, the thirty-fifth harmonic of the fundamental wave I1 isproduced with maximum value, the amplitudes of the thirty-fourth andthirty-sixth are suppressed 21.0 decibles relative to the amplitude ofthe thiry-fifth harmonic.

What is claimed is:

1. In a harmonic producer including a source of alternating currentwaves of fundamental frequency, a saturable-core coil connected to saidalternating current source, and an output circuit for said coil having acondenser and a substantially resistive load proportioned to producetherein a series of relatively sharp pulses of current occuring in apredetermined time relation; means comprising a direct current sourcefor biasing said saturable-core coil to change the time relation of theoccurrence of said pulses of current such that successive pulses areshifted the same amount of time.

2. In a harmonic producer including a saturable-core. coil, a source forapplying an alternating current wave of fundamental frequency theretoand an output circuit therefor, said output circuit including acondenser and a substantially resistive load proportioned to producetherein a series of relatively sharp positive and negative pulsesoccurring in a certain time relation; means comprising a direct currentsource for biasing said coil to vary the time relation of the occurrenceof said pulses so that the positive and negative pulses are respectivelyadvanced and delayed in predetermined equal amounts of time.

3. In a harmonic producer including a source of alternating currentwaves of fundamental frequency, a saturabIe-core inductance connected tosaid alternating current source, and an output circuit for saidinductance and having a condenser and a substantially resistive loadconnected therein and proportioned to provide in the inductance amagnetization characteristic such that successive pulses of current haveequal time spacings therebetween; and means comprising a unidirectionalcurrent source for biasing the inductance to shift the magnetizationcharacteristic in a manner such that the successive pulses of currenthave unequal time spacings therebetween.

4. In a harmonic producer comprising a saturable-core inductance, asource for impressing thereon an alternating current wave of fundamentalfrequency and an output circuit for the inductance, said output circuitincluding acoudenser and a highly resistive load proportioned to producetherein a broad range of odd harmonic frequency currents havinguniformly large amplitudes; means connected to the inductance andincluding a source of unidirectional current for producing apredetermined range of both odd and even harmonics, the current appliedto the inductance from said source of undirectional current beingproportioned so that the amplitude of a preselected harmonic is producedwith a maximum value relative to the amplitudes of adjacent harmonics inthe produced range of harmonics.

5. In a harmonic producer including a saturable-core inductance, asource for impressing thereon an alternating current wave of fundamentalfrequency and an output circuit for the inductance, said output circuitincluding a condenser and a highly resistive load proportioned toproduce therein a broad range of odd harmonic frequency currents ofuniformly large amplitudes; means connected to the inductance andincluding a source of unidirectional current for biasing the inductanceto produce odd and even harmonics of a range substantially equal to therange of odd harmonics, the current applied to the inductance from saidsource of unidirectional current being so proportioned that theamplitude of a preselected odd harmonic is produced with a predeterminedmaximum value while the amplitudes of the even harmonics adjacentthereto are suppressed.

6. In the harmonic producer according to claim 5 in which theunidirectional current is so proportioned that the amplitude oi a.preselected even harmonic is produced with a predetermined maximum valuewhile the amplitudes of the odd harmonics lying adjacent thereto aresuppressed.

7. In a harmonic producer comprising a saturable-core inductance, asource for impressing thereon an alternating current wave of fundamentalfrequency and an output circuit for said inductance, said output circuitincluding a condenser and a highly resistive load proportioned toproduce therein a broad range of odd harmonic frequency current havinguniformly large amplitudes; means connected to the inductance andincluding a source of unidirectional current for producing apredetermined range of both odd and even harmonics, the current appliedto the inductance from said source of unidirectional current beingproportioned so that a preselected group of both odd and even harmonicsis produced with substantially uniform amplitudes.

JACK M. MANLEY.

